Gill parasites of mummichogs, Fundulus heteroclitus (Teleostei: Cyprinodontidae): effects of season, locality, and host sex and size.

I investigated the prevalences and densities of gill parasites in 4 seasonal samples of mummichog, Fundulus heteroclitus (n=242), from 2 creeks differing in salinity in central Chesapeake Bay. The parasites (and overall prevalence ranges) were: mobile (12-88%) and sessile (0-50%) peritrichs (Ciliophora); Myxobolus funduli (58-94%) (Myxozoa); Gyrodactylidae (0-94%) (includes Gyrodactylus sp. and Fundulotrema sp.) and Salsuginus sp. (74-100%) (Monogenea); metacercariae of Phagicola diminuta (75-100%) and Echinochasmus schwartzi (79-100%) (Digenea); Ergasilus manicatus (25-100%) (Copepoda); Lironeca ovalis (0-11%) (Isopoda); and cysts of unknown etiology, or CUEs (64-94%) (unknown taxon). CUEs were more abundant in fall and gyrodactylids in winter. The myxozoan, copepod, and 1 species of digenean were most abundant in spring. Except for gyrodactylids and CUEs, densities were greater in the less saline creek for all taxa. There were no significant differences between sexes except in 1 sample; digenean densities increased with host length for females but not males. There was a strong positive relationship of CUE density with host length and weaker positive associations of gyrodactylid and Salsuginus sp. densities with host length.